JPH0256736A - Optical pickup head - Google Patents

Abstract

PURPOSE:To simplify a construction by crossing the magnetic circuit of a magnetic body having an inner yoke and an outer yoke with a focusing coil and two tracking coils. CONSTITUTION:At a frame part 31 of a cross section H type, a focusing coil 32 and tracking coils 33 and 34 are provided. The coil 32 is surrounded by the frame part 31 in three directions and at both edge surfaces of the frame part 31, coils 33 and 34 are coupled at both edge surfaces of the frame part 31. A U-shaped bent magnetic body 37 composed of an inner yoke 35 and an outer yoke 36 exists, the yoke 35 is inserted into a communicating hole of the coil 32, the yoke 36 sandwiches the coil 32, faces to the yoke 35 and the yoke 36 is extended up to the corresponding position of the coils 33 and 34. On the surface opposite to the coil 32 of the yoke 36, a magnetic 38 is coupled and a magnetic circuit is formed between yokes 35 and 36. By the driving force generating mechanism constituted like this, it is driven in the directions of arrow mark F and T (focus and tracking).

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention is applicable to information tracks on which digital signals are recorded at high density, such as CDs (compact discs), LVs (laser vigilance), optical cards, etc. The present invention relates to an optical pickup head that projects a light spot and optically writes and reads information.

(Prior Art) An optical pickup head is used as a mechanism for moving a light spot in two axial directions (focusing and tracking directions) to follow the surface wobbling and warping of an optical disk as a recording medium. FIG. 15 shows a conventional optical pickup head, in which a bobbin 8 in which a coil 5, 6, 7 is fitted is arranged in a magnetic circuit composed of a magnet 1.2 and a yoke 3.4. The objective lens 9 as a held objective optical system is driven in two axes (focus, tracking) directions. Inner yokes 12 and 13 are inserted into openings 10 and 11 provided inside the bobbin 8, so that the magnetic circuit is closed.

Further, the bobbin 8 is elastically supported by four support rods 14, - 16, and when these four support rods 14, - 16 are twisted together, the bobbin 8 is moved in the focus coil and tracking direction. is now moving.

The optical pickup head configured in this manner is provided with the yoke 3.4 and the magnet 1.2 as described above. In other words, two mechanisms for generating driving force are provided.

Two of these are provided in consideration of the balance of driving force. However, such a structure is not desirable in an optical pickup head that is desired to be smaller and lighter.

(WJ to be solved by the invention) A general optical pickup head has two driving force generation mechanisms.
However, there are problems in that not only the structure is complicated, but also the number of parts and man-hours are increased, which increases manufacturing costs.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an optical pickup head that can simplify the structure while maintaining the required performance, reduce the number of parts and assembly man-hours, and reduce production costs. With the goal.

[Structure of the invention]

(Means for Solving the Problem) An objective optical system is supported by a first support mechanism so as to be movable in the focusing direction with respect to the recording medium, and a second support mechanism supports the objective optical system so as to be movable in the tracking direction with respect to the recording medium. A driving force generating mechanism is provided which supports the objective optical system with a supporting mechanism and drives the objective optical system in the focusing direction and the tracking direction. In an optical pickup head, the inner yoke is surrounded by a focusing coil in a non-contact manner, and two tracking coils are provided on each side of the focusing coil.

(Function) One magnetic body having an inner yoke and an outer yoke is provided, and a focus coil and two tracking coils are provided so as to traverse the magnetic circuit formed by this magnetic body, thereby generating one driving force. The mechanism can be driven in two axes (focus and tracking), simplifying the structure.

(Embodiment) A first embodiment of the present invention will be described with reference to FIGS. 1 to 6. What is shown in FIG. 2 is the optical pickup head 17 in this embodiment, which has a bottom portion 18 and a movable frame 19 supported in a floating state on the bottom portion 18. The bottom portion 18 has a support portion 20 formed in a hexagonal shape, for example, and an extension having a protective frame 21 extending from the support portion 20 to protect first and second support mechanisms 24, 25, 27, and 28, which will be described later. It has a section 22. Further, the support portion 20 is provided with a support piece 23 extending vertically, and from this support piece 23, the protection frame 21
One end of two horizontal leaf springs 24, 25 as a first support mechanism, the other end of which is oriented to the side, are each coupled.

These horizontal leaf springs 24, 25 are horizontally provided above and below, and a connecting member 26 is connected to the other end. This connecting member 26 is connected to the horizontal leaf spring 24.25.
It extends in the width direction, and one ends of two vertical leaf springs 27 and 28 are respectively coupled to the ends in the width direction. The other ends of these vertical leaf springs 27 and 28 are extended so as to sandwich the support piece 23, and are connected to the movable frame 19.

A light passing hole (not shown) communicating in the vertical direction is provided in a substantially central portion of the movable frame 19, and an objective lens 29 serving as an objective optical system is provided in this light passing hole.

Furthermore, the movable frame 19 and the support section 20 have a first
A driving force generating mechanism 30 as shown in the figure is provided. This driving force generating mechanism 30 is provided with a focus coil 32 and a tracking coil 3, which will be described later, with respect to a frame portion 31 formed within the single moving frame and having an H-shaped cross section in the vertical direction.
3.34 is provided. Here, the focus coil 32 is connected to the wall surface of the frame portion 31 so as to be surrounded on three sides, and is wound so that an insertion hole communicating in the vertical direction is formed in the center. In addition, the frame portion 3
The focus coil 3 is mounted on the wall surface formed at both ends of the focus coil 3.
These tracking coils 33.3 are coupled with two tracking coils 33.34 sandwiching the two tracking coils 33.3.
4 is formed by winding the wire so that the center is in the tracking direction. Here, the upper and lower ends of the frame portion 31 are coupled to the inner surface of the movable frame 19.

On the other hand, a magnetic body 37 consisting of an inner yoke 35 and an outer yoke 36 is provided on the support portion 20 side. This magnetic body 37 has a cross section in the left and right direction bent into a substantially U-shape,
The lower surface is coupled to the support portion 20 . The inner yoke 35 is inserted into the communication hole of the focus coil 32, and the outer yoke 36 is positioned to face the inner yoke 35 with the focus coil 32 in between. This outer yoke 36 is connected to the tracking coil 33.
-134.

A magnet 38 is coupled to the surface of the outer yoke 36 facing the focus coil 32, so that a magnetic circuit is formed between the inner yoke 35 and the outer yoke 36.

By being configured as described above, it is possible to drive in the direction of the arrow FST (focus, tracking) shown in FIG.

That is, as shown in FIGS. 3 and 4, the focus coil 32 is
By passing a current in the depth direction with respect to the drawing, the focus coil 32 moves in the direction of arrow A as shown in the drawing.

Furthermore, the focus coil 32 is moved upward by causing the current to flow through the coil in the opposite direction, that is, toward the front in the drawing. The movement at this time is made possible by the elastic deformation of the horizontal leaf springs 24.25, and the movable frame 19 is moved in parallel by these two horizontal leaf springs 24.25.

On the other hand, as shown in FIG. 5, a magnetic field indicated by arrow M is also formed in the tracking coils 33 and 34, and forces Fl and F2 are generated. This force F1
, F2 are combined as shown in FIG. 6, the force components in the direction orthogonal to the tracking direction cancel each other out, and only the force component F3 in the tracking direction is applied. Conversely, when moving the movable frame 19, control can be achieved by passing a reverse current to the tracking coils 33, 34. In other words, the tracking coil 33.
By providing two 34, all force components other than those in the tracking direction are canceled out. The moving frame 19 is moved in parallel by elastic deformation of the two vertical leaf springs 27 and 28.

As described above, the driving force generating mechanism 30 is constituted by the focus coil 32, the tracking coils 33, 34, the magnetic body 37 having the inner yoke 35 and the outer yoke 36, and the magnet 38 coupled thereto. It is possible to drive in the focus and tracking directions with a very simple structure compared to the conventional structure. This makes it possible to reduce the size and weight, reduce the number of parts and man-hours by about half, and reduce production costs. Further, the magnet 38 is formed into a substantially rectangular plate shape, and because of its simple shape, the cost of parts can be kept low. In addition, conventionally two magnets were required, but by providing two tracking coils 33 and 34, the magnet 38
Since the number of expensive magnets is reduced compared to coils, costs can be reduced.

Other embodiments will be described below, but since the structure of the driving force generating mechanism is the same as described above, only the mechanism that supports the objective optical system so that it can move in the focusing direction and the tracking direction will be described.

The optical pickup head 17 shown in FIG. 7 is a second embodiment of the present invention, and the bottom portion 39 is in the shape of a rectangular plate, and a support body 40 is integrally formed on the upper surface of the end portion. On the central side of the support body 40, there are four support rods 41, 42., two at the top and two at the bottom.
The ends of 43 are elastically connected. A moving frame 44 is provided at the tip of these support rods 41, 42, 4B.
are elastically connected. This moving frame 44 is provided with an objective lens 45, and is also provided with a driving force generating mechanism 30 shown in FIG.

A third embodiment of the present invention is constructed as shown in FIG. 8, and is provided with a cylindrical vertical shaft 47 on the bottom portion 46, and is movable in the vertical direction and the circumferential direction around this vertical shaft 47. Possibly a moving body 48 is provided. The movable body 48 and the bottom portion 46 are provided with a driving force generating mechanism 30 shown in FIG. Further, the axis 4 is perpendicular to the position where the driving force generating mechanism 30 of the movable body 48 is provided.
An objective lens 49 is provided on the opposite side of the lens 7.

A fourth embodiment of the present invention will be described below with reference to FIG. 9. Optical pickup head 1 shown in the figure
7 is provided with a support body 51 on the upper end side of the bottom part 50, and the ends of two upper and lower support rods 52, 53, and 54 are elastically connected to the central side surface of this support body 51. The proximal end surface of the movable body 55 is elastically connected to the distal ends of these support rods 52, 53, and 54, respectively. An objective lens 56 is provided at the center of the movable body 55, and a driving force generating mechanism 30 shown in FIG. 1 is provided at the distal end side.

A fifth embodiment of the present invention is constructed as shown in FIG. 10, and a cylindrical vertical shaft 57a is provided on the upper surface of the end portion of the bottom body 57. A base end portion of a movable body 58 is provided on this vertical shaft 57 so as to be movable in the vertical direction and the circumferential direction. An objective lens 59 is provided at the center of the movable body 58, and a driving force generating mechanism 30 configured as shown in FIG. 1 is provided at the tip.

The optical pickup head 17 shown in FIG. 11 is a sixth embodiment of the present invention, and a support body 61 is provided on the upper end side of the bottom part 60, and two parts are provided above and below the support plate 61.
The proximal ends of the horizontal leaf springs 62 and 63 are connected to each other. A connecting body 64 is connected to the tips of these horizontal leaf springs 62 and 63, and this connecting body 64 has two
The proximal ends of the vertical leaf springs 65, 66 are connected. Here, the vertical leaf springs 65 and 66 are the horizontal leaf springs 62 and 62.
．． 63, and a connecting portion 68 of a movable body 67 is connected to the distal end. The connecting portion 68 of the movable body 67 has a mounting portion that is vertically penetrated, and the connecting portion 68 is located in this mounting portion. With this configuration, the movable body 67 is supported movably with respect to the bottom portion 60 in the focusing direction and the tracking direction. An objective lens 69 is provided at the center of the movable body 67, and a driving force generating mechanism 30 configured as shown in FIG.
is provided.

A seventh embodiment of the present invention will be described below with reference to FIG. 12. The optical pickup head 17 in this embodiment has a support portion 71 formed on the upper surface of the center portion of the bottom portion 70 . The base ends of a total of two horizontal leaf springs 72 and 73 are connected to one side of the support part 71 on the upper and lower sides, respectively.
A connecting portion 74 is coupled to the tip of the horizontal leaf spring 72, 73. The base ends of vertical leaf springs 75 and 76 are connected to the left and right ends of the connecting portion 74, respectively. These vertical leaf springs 75 and 76 are provided in parallel and extend so as to sandwich the support portion 71 therebetween. A proximal end portion of a movable body 77 is coupled to the distal end of the support portion 71 . An objective lens 78 is provided at the center of the movable body 77, and a driving force generating mechanism 30 shown in FIG. 1 is further provided at the tip.

The optical pickup head 17 shown in FIG. 13 is an eighth embodiment of the present invention, and support pieces 80 and 81 are provided on the left and right sides of the center of the upper surface of the bottom portion 79. A horizontal leaf spring 82 is mounted on each of the same side surfaces of these support pieces 80 and 81,
The proximal ends of ~85 are each connected. Here, two of the horizontal plate springs 82, - 85 are provided, and they are provided vertically in parallel for each of the same support pieces 80 and 81. The same connecting portion 88 is connected to the distal ends of these horizontal leaf springs 86 and 87, and the base ends of two vertical leaf springs 89 and 90 are connected to the center side of this connecting portion 88. There is. These vertical leaf springs 89.90 are extended to the vicinity between the support pieces 80.81, and have a movable body 9 at the tip.
The proximal ends of 1 are connected. An objective lens 92 is provided at the center of the movable body 91, and a first objective lens 92 is provided at the tip.
A driving force generating mechanism 30 shown in the figure is provided.

A ninth embodiment of the present invention will be described below with reference to FIG. 14. The optical pickup head 17 shown in the figure has two supporting pieces 94 and 95 at the center left and right sides of the upper surface of the bottom part 93.
is provided. The base ends of vertical leaf springs 96 and 97 are respectively coupled to one side of these support pieces 94 and 5. These vertical leaf springs 96 and 97 are provided in parallel, and a connecting portion 98 is coupled to each other's tip ends.

There are two horizontal leaf springs 9 on the center side of the connecting part 98.
9.100 proximal ends are connected. These horizontal leaf springs 99, 100 are positioned vertically and parallel to each other, and extend to the vicinity of the support pieces 94, 95. The base end of the movable body 101 is connected to the distal end portions of these vertical leaf springs 96 and 97. An objective lens 102 is provided at the center of the movable body 101, and a driving force generating mechanism 30 shown in FIG. 1 is provided at the tip.

The optical pickup radar 17 configured as shown in the second to ninth embodiments is provided with a support mechanism that supports the optical pickup so as to be movable in the focusing direction and the tracking direction, and a moving object supported by this support mechanism is supported. Driving force generation mechanism 3
By configuring the lens to be driven in the focus direction and the tracking direction by 0, it is possible to obtain substantially the same effects as in the first embodiment.

〔Effect of the invention〕

The structure for driving the objective optical system in the focus direction and the tracking direction can be simplified compared to the conventional structure, and the number of parts can be reduced to about half. Thereby, the number of manufacturing steps can be reduced and manufacturing costs can be reduced.

[Brief explanation of the drawing]

1 to 6 show a first embodiment of the present invention,
FIG. 1 is a perspective view showing the driving force generation mechanism, FIG. 2 is a perspective view showing the optical pickup head, FIG. 3 is a sectional view taken along the line ■-■ shown in FIG. 1, and FIG. Figure 3 is a vector diagram showing the force acting on the coil in Figure 5. Figure 5 is a plan view of the driving force generation mechanism. Figure 6 is a vector diagram showing the combination of the forces acting on the coil in Figure 5. Figure ff17 is a vector diagram showing the force acting on the coil in Figure 5. A perspective view of the second embodiment, FIG. 8 is a perspective view of the third embodiment of the present invention,
9 is a perspective view of a fourth embodiment of the present invention, FIG. 10 is a perspective view of a fifth embodiment of the present invention, FIG. 11 is a perspective view of a sixth embodiment of the present invention, and FIG. 12 is a perspective view of a fifth embodiment of the present invention. FIG. 13 is a perspective view of the eighth embodiment of the invention, FIG. 14 is a perspective view of the ninth embodiment of the invention, and FIG. 15 is a perspective view of a conventional example. It is. 17... Optical pickup head, 24.25... Horizontal plate spring (first support mechanism), 27.28... Vertical plate spring (second support mechanism), 29... Objective lens (objective optical system) ), 30... Driving force generation mechanism, 32... Focus coil, 33.34... Tracking coil, 35
...Inner yoke, 36...Outer yoke, 37...Magnetic material, 38...Magnet.

Claims (1)

[Claims] an objective optical system that focuses a laser beam on the surface of a recording medium; a first support mechanism that supports the objective optical system so as to be movable in the focus direction with respect to the recording medium; In the optical pickup head, the optical pickup head includes a second support mechanism that supports the objective lens movably in the tracking direction, and one driving force generating mechanism that drives the objective lens in the focusing direction and the tracking direction, wherein the driving force generating mechanism is attached to the inner yoke. a magnetic body having an outer yoke; a magnet attached to the outer yoke of the magnetic body to form a magnetic circuit; a focus coil surrounding the inner yoke in a non-contact state; An optical pickup head comprising two tracking coils located in one position.